Mower drive wheel biasing member being a non-metal biasing member

ABSTRACT

The mower front independent suspension assembly in some embodiments of the present invention includes a first suspension arm connected to the front of the lawn mower frame and a second suspension arm connected to the side of the lawn mower frame. In some embodiments, the first suspension arm is connected to the front of the frame at or near the longitudinal center of the frame, while the second suspension arm is connected to the side of the frame a distance from the front of the frame. Also, in some embodiments the cutter deck of the lawn mower is connected to the front independent suspension assemblies for movement therewith.

REFERENCE TO RELATED APPLICATIONS

This is a continuation of U.S. patent application Ser. No. 11/062,901filed on Feb. 22, 2005, now U.S. Pat. No. 7,152,389 which is acontinuation of U.S. patent application Ser. No. 10/285,350 filed onOct. 31, 2002 and issued as U.S. Pat. No. 6,857,254, which is acontinuation-in-part of U.S. patent application Ser. No. 09/879,800filed on Jun. 12, 2001 and issued as U.S. Pat. No. 6,510,678, which is acontinuation of U.S. patent application Ser. No. 09/384,534 filed onAug. 27, 1999 and issued as U.S. Pat. No. 6,244,025, which in turn is acontinuation-in-part of U.S. patent application Ser. No. 09/359,537filed on Jul. 22, 1999 and issued as U.S. Pat. No. 6,460,318, which inturn is a continuation-in-part patent application of (i) U.S. patentapplication Ser. No. 09/144,499, filed Aug. 31, 1998 and issued as U.S.Pat. No. 5,946,893, which in turn claims benefit from U.S. ProvisionalPatent Application Ser. No. 60/063,362 filed on Oct. 28, 1997; (ii) U.S.patent application Ser. No. 09/119,818 filed on Jul. 21, 1998 and issuedas U.S. Pat. No. 6,170,242, which in turn claims benefit from U.S.Provisional Patent Application Ser. No. 60/053,403 filed on Jul. 22,1997 and U.S. Provisional Patent Application Ser. No. 60/063,362, filedon Oct. 28, 1997; and (iii) U.S. patent application Ser. No. 08/898,801,filed on Jul. 23, 1997 and issued as U.S. Pat. No. 6,062,333, which inturn claims benefit from U.S. Provisional Patent Application Ser. No.60/022,865 filed on Jul. 26, 1996, all of which are incorporated hereinby reference.

BACKGROUND OF THE INVENTION

The present invention is described with respect to its use on lawnmowers, particularly self-propelled machines fitted with rotating bladesfor cutting grass and other vegetation. Numerous mowers exist in themarketplace for grass and vegetation. However, many of these mowers canproduce uneven cuts and deliver unwanted stresses from the terrain tothe driver and mower, resulting in driver fatigue and discomfort, mowerwear and tear, more frequent repairs, and a shorter mower life.

In many typical mowers, the cutter deck is suspended as either aground-following deck or a floating deck. A ground-following decktypically rides on caster wheels (e.g., a set of two or four casterwheels in many cases) and follows the contours of the ground. A floatingdeck is often suspended beneath the chassis between the front and rearwheels, such as by chains, sets of links and other elements. Otherfloating decks are suspended in various manners over the ground at alocation in front of, behind, or beside the lawn mower frame. Thefloating deck is raised when skids, wheels, rollers, or other elementsattached to the deck contact the lawn surface.

The height of a floating cutter deck from the surface being cut is oftendefined at least in part by the elevation of the mower's chassis.Generally, the intent for such a deck suspension system is to avoidcontinuing contact with the earth surface. When a cutter deck travelsover uneven terrain having a strong grade, the cutter deck can contactthe earth surface, and can cause the lawnmower blade(s) therein to scalpthe surface being cut.

Cutter decks are generally designed to avoid scalping by rising orfloating upwardly. This generally works for certain kinds of earthunevenness, but some scalping still occurs on severe terrain. Even ifscalping can be avoided, cutter deck height relative to the earthsurface can vary widely. This is also undesirable because it results inan unequal height of the cut grass.

A significant number of lawnmowers have wheels that are rigidly attachedto the mower chassis. Unfortunately, when a mower having such asuspension encounters uneven terrain, the mower chassis can respond withsignificant upward and downward movement.

With regard to lawnmower front wheels, many conventional lawn mowerdesigns either rigidly connect the front wheels to the chassis as justmentioned or employ a single axle to which the front wheels areattached. In some cases, the single axle can pivot about a point betweenthe wheels, thereby generating slightly improved performance. Whetherrigidly secured to the chassis or connected to a common axle, such frontsuspension designs either do not eliminate the undesirable upward anddownward chassis movement described above, or only do so to a verylimited extent. For example, if one wheel of such a mower rises inresponse to a rise in terrain, the single axle would cease to beparallel with the earth surface, generating forces that bring thechassis and cutter deck also out of a parallel relationship with theearth surface. The resulting cut of the grass is uneven andunsatisfactory.

In these and other conventional mowers, improved spring suspensionsystems are employed to reduce the amount of vertical chassis motionwhen one or more wheels encounter unevenness in the earth surface beingtraversed. These spring systems improve traction of such mowers bymaintaining improved contact between the wheels and the surface beingtraversed. However, these spring suspension systems can cause or allowthe chassis to roll relative to the cutting surface, such as, forexample, when a mower is turned sharply or navigates a steep hillside.When a chassis rolls, a floating cutter deck (and in many cases, even aground-following cutter deck) rolls with the chassis, resulting in oneside of the cutter deck being closer to the cutting surface than theother. Consequentially, the cut of the grass is uneven andunsatisfactory.

In order to address cutting quality, rider comfort, and suspension wearproblems, many conventional lawn mowers employ suspensions having one ormore springs. Although such spring suspensions do represent animprovement and can help to address these problems, significant room forimprovement still exists. For example, heavy riders or heavy moweraccessories (e.g., grass catchers) tend to exert extra stress on thesuspension springs, potentially causing the suspension springs to“bottom out” or to provide a limited range of spring motion. In eithercase, an uncomfortable ride results because the spring has limited or nocapacity to absorb shock. As a result, an increased amount of shock istransferred to the mower and operator. The increase in shock cansignificantly shorten the life of the mower and can be a cause of morefrequent mower maintenance and repair. Substituting a stiffer spring forheavy loading situations is an unattractive solution for many reasons,such as an uncomfortable ride in a light loading situation andadditional low-level vibrations transmitted to the chassis.

In light of the shortcomings and problems of prior art lawn mowersdescribed above, a need exists for a lawn mower having a suspensionsystem that improves floating cutter deck and/or ground-following cutterdeck motion, results in better cutting performance and quality, isrelatively simple and inexpensive in construction, can limit undesirablechassis movement (such as chassis roll and large vertical chassismovement), provides a more comfortable ride, and can help prevent mowerdamage from vibration and shock. Each embodiment of the presentinvention provides one or more of these results.

SUMMARY OF THE INVENTION

Some embodiments of the present invention address one or more of theproblems and limitations of the prior art by a unique connectionassembly of the front wheels to the lawn mower frame. In someembodiments, the connection assembly for each front wheel includes afirst suspension arm connected to the front of the frame and a secondsuspension arm connected to the side of the frame. The first suspensionarm can be connected to the front of the frame at or near thelongitudinal center of the frame, while the second suspension arm can beconnected to the side of the frame a distance from the front of theframe. Either or both suspension arms can be mounted to the frame viaplates secured to the frame. In some embodiments, the suspension armsare pivotably connected to the frame. Either or both suspension arms canbe connected directly to a wheel yoke, can be connected to a supportplate extending between the suspension arms, or can be connected to thewheel yoke and to a support plate extending between the suspension arms.

In some embodiments, front suspension assemblies are employed that haveone or more springs positioned to bias the associated front wheel in adownward direction. The spring(s) can be located between the frame andthe support plates (where used), can be located between either or bothof the arms and the frame, or in still other manners to generate thesame desired force. If desired, each suspension assembly can be providedwith a spring, air bag, pneumatic or hydraulic cylinder, or other suchdevice that compensates for heavy loads upon the suspension assemblies(i.e., “load compensation adjusters”). In some embodiments, the loadcompensation adjusters are adjustable to change the resistance todownward force provided by the associated suspension assemblies.

As described above, many conventional lawn mowers suffer from scalpingand uneven cutting problems when the lawn mowers traverse unevensurfaces. Some embodiments of the present invention substantially reducescalping and uneven cutting by suspending each of the front wheelsindependently from the front frame of the lawn mower with the structuredescribed above. Upon wheel contact with uneven ground such as a steepupward or downward grade, the front wheels are therefore able to movegenerally vertically without greatly altering the relationship of theframe with respect to the surface traversed, or at least with reducedmovement of the frame. In this manner, roll and pitch of the frame canbe significantly reduced, resulting in a higher-quality cut and animproved ride.

By employing a two-arm spring suspension assembly connected as describedabove, the inventors have discovered that far less damaging vibration,shock, and impact received by the front wheels are transmitted to theframe and to the operator. By reducing the transmission of suchvibration, shock, and impact shock to the chassis, the life of the lawnmower is considerably extended and the need for maintenance and repairis decreased.

In some embodiments of the present invention, the cutter deck isconnected to the front and/or rear suspensions, and therefore move withvertical movement of the front and/or rear suspensions. In this manner,the cutter deck can follow the terrain traversed by the mower byfollowing the vertical movement of the mower wheels.

In these and other embodiments, the front and/or rear suspension systemscan be independent, and can be connected to a beam, subframe, or otherstructure that is pivotably coupled to the mower frame, therebytransmitting upward and downward force to the independent suspensions aswell as to the pivoting beam, subframe, or other structure. Regardlessof whether the cutter deck is also connected to these independentsuspensions, this arrangement can result in improved suspension andcutter deck movement.

In addition, due to decreased vibration, shock, and impact transmittedby various embodiments of the present invention, a lawn mower providedwith a suspension according to some embodiments the present inventioncan be operated at quicker speeds, resulting in increased lawn mowerefficiency and decreased time needed to cut a surface. Also, therelatively simple design of some wheel suspensions according the presentinvention enables the suspension to be included in lawn mowers withlittle impact upon manufacturing and sales costs.

Other features and advantages of the present invention will becomeapparent to those skilled in the art upon review of the followingdetailed description, claims, and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is further described with reference to theaccompanying drawings, which show various embodiments of the presentinvention. However, it should be noted that the invention as disclosedin the accompanying drawings is illustrated by way of example only. Thevarious elements and combinations of elements described below andillustrated in the drawings can be arranged and organized differently toresult in embodiments which are still within the spirit and scope of thepresent invention.

In the drawings, wherein like reference numerals indicate like parts:

FIG. 1 is a perspective view of a lawn mower having a front suspensionsystem according to an embodiment of the present invention;

FIG. 2 is a side elevation view of the lawn mower of FIG. 1;

FIG. 3 is a sectional perspective view of the front suspension system ofthe lawn mower illustrated in FIGS. 1 and 2;

FIG. 4 is a sectional perspective view of the front suspension system ofthe lawn mower illustrated in FIGS. 1-3;

FIG. 5 is a front elevation view of the lawn mower of FIG. 1;

FIG. 6 is a partial perspective view of a rear suspension systemaccording to an embodiment of the present invention;

FIG. 7 is a partial perspective view of a portion of the rear suspensionsystem of FIG. 6;

FIG. 8 is a partial side elevation view of a portion of the rearsuspension system illustrated in FIGS. 6 and 7;

FIG. 9 is a partial rear elevation view of a portion of the rearsuspension system illustrated in FIG. 6;

FIG. 10 is a partial rear elevation view of a portion of a rearsuspension system according to another embodiment of the presentinvention;

FIG. 11 is a partial sectional view of a pre-compressed spring used therear suspension system according to yet another embodiment of thepresent invention;

FIG. 12 is a cutaway view of a load compensation adjuster according toan embodiment of the invention, shown installed in the rear suspensionsystem of FIGS. 6-9;

FIG. 13 is an elevation view of the load compensation adjuster of FIG.12;

FIG. 14 is an elevation view of a shock absorber embodiment of the loadcompensation adjuster of the present invention;

FIG. 15 is an elevation view of an air shock embodiment of the loadcompensation adjuster of the present invention;

FIG. 16 is an elevation view of an airbag embodiment of the loadcompensation adjuster of the present invention;

FIG. 17 is an elevation view of an airbag embodiment of the loadcompensation adjuster of the present invention;

FIG. 18 is a partial view of a front or rear suspension system accordingto an embodiment of the present invention;

FIG. 19 is a partial view of a front or rear suspension system accordingto another embodiment of the present invention;

FIG. 20 is a perspective view of a mower having a front suspensionsystem according to yet another embodiment of the present invention;

FIG. 21 is a perspective view of a mower having a front suspensionsystem according to another embodiment present invention;

FIG. 22 is an exploded perspective view of the mower frame and frontwheel independent suspension assemblies shown in FIG. 21;

FIG. 23 is an assembled perspective view of the mower frame and frontwheel independent suspension assemblies shown in FIGS. 21 and 22;

FIG. 24 is an exploded perspective view of the mower deck lift assemblyshown in FIG. 21;

FIG. 25 is a top plan view of the mower frame and front wheelindependent suspension assemblies shown in FIGS. 21-24;

FIG. 26 is a front view of the mower frame and front wheel independentsuspension assemblies shown in FIGS. 21-24;

FIG. 27 is a perspective view of a mower having a front suspensionsystem according to another embodiment of the present invention;

FIG. 28 is an exploded perspective view of the mower frame and frontwheel independent suspension assemblies shown in FIG. 27;

FIG. 29 is an assembled perspective view of the mower frame and frontwheel independent suspension assemblies shown in FIGS. 27 and 28;

FIG. 30 is an exploded perspective view of the mower deck lift assemblyshown in FIG. 27;

FIG. 31 is a perspective view of a mower having a front suspensionsystem according to another embodiment of the present invention;

FIG. 32 is an exploded perspective view of the mower frame and frontwheel independent suspension assemblies shown in FIG. 30;

FIG. 33 is an assembled perspective view of the mower frame and frontwheel independent suspension assemblies shown in FIGS. 31 and 32; and

FIG. 34 is an exploded perspective view of the mower deck lift assemblyshown in FIG. 31.

DETAILED DESCRIPTION

Referring to FIGS. 1-2, a lawn mower 10 includes a seat 12 connected toa chassis 14. Chassis 14 in turn rests on a main frame 16. Two rearwheels 18 are connected to main frame 16 by the independent suspension(not shown) as described in co-pending U.S. patent application Ser. No.09/119,818. Two front wheels 22 are connected to main frame 16 via afront suspension system, shown generally at 24. A floating cutter deck20 is preferably suspended beneath main frame 16 by rear suspensionchains 26 and front suspension chains 28. Each rear suspension chain 26is preferably connected to a rear wheel bracket 30 which is “wheel-side”of the rear independent suspension system. Each front suspension chainis preferably connected to a deck height adjustment mount 32 which ispart of front suspension section 24. Suspending cutter deck 20 from the“wheel-side” of the front and rear independent suspensions ensures thatcutter deck 20 moves vertically up and down in response to the verticalmotion of front wheels 22 and rear wheels 18, which in turn areresponsive to the terrain being mowed. Scalping and uneven cuts of thegrass are thus prevented.

Although the mower of the present invention can be equipped with eithera ground-following cutter deck or a floating cutter deck, using afloating cutter deck with a mower having independent suspension requiresadditional considerations. Rolling of a lawn mower chassis is inducedunder certain situations. Among them are: (a) when the mower changesdirection while traveling forward and centrifugal force acts laterallyat the center of gravity of the machine; (b) when the mower traverses aslope and the gravitational force vector shifts direction relative tothe plane of the mower wheel tread, and (c) when the mower travels overa surface undulation, lifting or lowering one or both wheels on oneside, thereby rotating the mower chassis in space.

Conventional mowers typically use wheels that are rigidly connected tothe chassis. In these mowers, the chassis cannot roll relative to thewheels; therefore, there is no rolling of types (a) and (b). Otherconventional mowers have a pivoting front or rear axle at one end, withan opposing end axle rigidly attached to the chassis. In these mowers,the rigidly attached axle limits the chassis roll which the pivotingaxle otherwise permits to the extent the chassis is sufficiently rigid.The mower of the present invention, preferably having both front andrear independent wheel suspension systems, beneficially minimizes anyrolling of the machine when a wheel passes over certain small bumps anddepressions—type (c) rolling. Nonetheless, larger bumps and depressionscan induce rolling.

As will be explained below, the suspension configuration of FIG. 9 isprone to rolling of types (a) and (b). if cutter deck 20 of mower 10 issuspended from the chassis, rolling may adversely affect the essentialmower function, that is, cutting grass to an even height. In particular,when the chassis rolls and one side moves closer to the earth surface, acutter deck suspended from the chassis also moves closer to the surface.Therefore, the preferable embodiment of the present invention couplesthe motion of the cutter deck to the motion of a sprung wheel ratherthan directly to the chassis, thereby reducing the change in cutter deckheight relative to the mowed surface when the chassis rolls.

Due to the large cutting width preferred in commercial mowers and thedistance between the front wheels 22, rocks or other uneven terrainfeatures that are avoided by front wheels 22 can damage cutter deck 20.Cutter deck 20 therefore preferably includes a front roller 34, a rearroller 36 (partially hidden by rear wheel 18 in FIG. 2), and frontcaster wheels 38 that protect cutter deck 20 from damage.

Referring to FIGS. 3-5, front suspension system 24 includes alongitudinal suspension strut 40 that is connected to main frame 16 viaan upper suspension strut 42 and a lower suspension strut 44. Frontwheel 22 is connected to longitudinal strut 40 via a trunnion 39. Upperand lower suspension struts 42, 44 pivotably connect to main frame 16 ata plurality of main frame pivot points 46 and pivotably connect tolongitudinal suspension strut 40 at a plurality of front suspensionpivot points 48. A spring 50 is fixed between a spring bracket 52 ofupper suspension strut 42 and a front transverse member 54 of main frame16 so that upward movement of suspension system 24 compresses spring 50between spring bracket 52 and front transverse member 54. Upper andlower suspension struts 42, 44 are preferably of equal length so thatthe suspension travel does not change the perpendicularity of frontwheel 22 to the ground.

As front wheels 22 move vertically up and down in response to theterrain, the front of cutter deck 20, being connected to longitudinalsuspension strut 40 via adjustment mount 32, moves vertically up anddown in response to the vertical motion of front wheels 22. Main frame16 is isolated from the vertical motion of front wheels 22 by frontsuspension system 24.

Referring to FIGS. 6-9, a rear suspension system for mower 10 includes amotor mount 86 connected to main frame 16 via upper links 62 and lowerlinks 64. Two struts 78 join an upper frame member 74 of main frame 16to a lower frame member 76 of main frame 16. Upper and lower links 62,64 are connected to struts 78 at main frame pivot points 66 and to motormount 86 at rear suspension pivot points 68. Upper and lower links 62,64 are shown in this embodiment as being of equal length. A spring 72 iscaptured between a spring bracket 70 of upper frame member 74 and amotor 80. FIG. 8 additionally shows an optional disk 84 on a wheel hub82 that is used with disk brakes instead of the more conventionalband-drum brakes typically used on prior art lawn mowers.

Referring specifically to FIG. 9, a roll center is an imaginary pointabout which a mower with movable suspension elements tends to roll whensubjected to lateral forces. A roll axis of the mower runs through thefront and rear roll centers. The location of a roll center R for therear wheel suspension system is determined by examining the intersectionof an upper link phantom line 90 and a lower link phantom line 89. Line90 runs through the pivot points for upper link 62 while line 89 runsthrough the pivot points for lower link 64. A ground contact phantomline 88 runs from a ground contact point 92, representing the contactbetween rear wheel 18 and ground 94, to the intersection of lines 90 and89. In the embodiment described above, where upper and lower links 62,64 are of equal length, lines 90 and 89 intersect at infinity. Line 88therefore intersects lines 90 and 89 at infinity; line 88 is thusparallel to lines 90 and 89. The intersection of line 88 with a verticalplane passing through a center of gravity (mass) of the mower is thelocation of roll center R.

In this embodiment, roll center R is substantially lower in elevationthan the center of gravity CG of the mower. The location of roll centerR can be moved vertically by changing the lengths and angles of the linkassemblies. With roll center R significantly below center of gravity CG,the mower tends to sway or rock to the side when turning. Sway bars (notshown), also known as anti-sway or anti-roll bars, are optionally addedto this equal-link-length suspension to inhibit swaying during turning.Such bars are typically torsion bars or other elastic structure which,when one wheel moves closer to the chassis, resist such motion with aforce, the reaction to which is applied to the opposite wheel.Notwithstanding the tendency to roll, the FIG. 9 suspension provides abetter vehicle ride and absorption of bumps compared to an unequallink-length suspension. The FIG. 9 suspension also minimizes lateralmotion when the mower load changes, such as when an operator mounts ordismounts the mower, removes a grass-catcher bag, or when there arechanges in the mower's vertical momentum due to uneven terrain.

Referring to FIG. 10, an embodiment is shown with unequal link lengths.An upper link 62′ is shorter than a lower link 64′, with the lengths oflinks 62′, 64′ preferably determined such that the roll center R and thecenter of gravity CG substantially coincide. As shown in the figure,phantom lines 90′ and 89′ intersect at R, so ground contact line 88′intersects the vertical plane passing through the center of gravity CGat the center of gravity CG. This configuration minimizes the rolltendency of the mower during turning.

Referring to FIG. 11, a way of pre-compressing spring 72 is shown.Pre-compression is desirable to lessen the movement of the mower chassiswhen the mower operator mounts and dismounts the mower. Pre-compressionis preferably accomplished by pivotably attaching a threaded guide rod96 to motor 80. Rod 96 extends through a hole 97 in spring bracket 70with a nut 98 on the threaded end of rod 96. Nut 98 is preferablyadjustable so that the amount of pre-compression can be changed whenrequired.

Referring to FIGS. 12-13, a load compensation adjuster such as overloadspring 100 is installed inside spring 72. If suspension spring 72 is aclosed, ground end, compression spring with a right hand helix, overloadspring 100 is preferably a closed, ground end, compression spring with aleft-hand helix. Overload spring 100 fits inside spring 72 and isapproximately one inch shorter in length than spring 72. The shorterlength of overload spring 100 allows spring 72 to operate at itsexisting rate, but when spring 72 is compressed more than one inch,overload spring 100 begins to help carry the extra weight. Overloadspring 100 is preferably wound with coils in the opposite direction fromspring 72. The characteristics of the preferred embodiment of overloadspring 100 is detailed in Table 1.

Spring type compression spring, closed and grounded end Material chromesilicon Wire Diameter 0.2340 in. Mean Diameter 1.0160 in. Insidediameter 0.7820 in. Outside Diameter 1.2500 in. Total Coils 15.6984 in.Pitch 0.3308 in. Pitch Angle 5.9177 deg. Weight 0.6120 lbs. Free Length5.0000 in. Solid Height 3.6734 in. Load Rate (lbs./in.) 5.00 in. (freelength) @ 0 lbs. @150 lbs. 4.50 in. @300 lbs. 4.00 in. @398 lbs. 3.67in. (solid height)

Referring to FIG. 14, load compensation adjustment is achieved using analternative embodiment such as a shock absorber 102 inside spring 72 inplace of overload spring 100. This arrangement is commonly referred toas a coil-over suspension.

Referring to FIG. 15, load compensation adjustment is achieved using analternative embodiment such as an air shock 104 instead of shockabsorber 102, although not depicted inside spring 72 in the figure.Using air shock 104 allows adjustment of the spring tension by raisingor lowering the air pressure, thereby determining the spring load ortension.

Referring to FIG. 16, load compensation adjustment is achieved by usingan alternative embodiment such as an airbag 106 to replace overloadspring 100 inside spring 72. Airbag 106 can be inflated or deflated forthe desired suspension, either by the user of pre-inflated at thefactory.

Referring to FIG. 17, an alternative embodiment for load compensationadjustment includes an airbag 108 which could replace the spring withina spring combination by acting as a variable compression spring. As theair in airbag 108 becomes compressed, the force required to compress itfurther increases.

Referring to FIG. 18, a torsion bar suspension is shown connected towheel hub 82 at the left rear wheel location for mower 10. A firsttorsion bar 112 is hooked to lower link 64 at one end, while another endattaches to an adjuster 114, which permits adjustment of the tension oftorsion bar 112. In similar fashion, a second torsion bar 110 is hookedto the lower link 64 on the right side of mower 10, with the other endof torsion bar 110 being attached to an adjuster 116 which is connectedto lower link 64 on the left side of mower 10. The right side wheel huband upper and lower links are not shown in FIG. 18. The torsion bars110, 112 replace the springs 72 to provide the rear wheel suspension.Load compensation is done with adjusters 114, 116. Although the torsionsuspension is shown for the rear wheels, it can be used on the frontwheels as well. For the front suspension system shown in FIG. 4, fronttransverse member 54 and springs 50 are replaced by the torsion bars inthe manner just described with respect to the rear suspension system.

Referring to FIG. 19, an alternative embodiment of the front suspensionsystem includes a torsion bar 118 attached to lower suspension strut 44near the lower main frame pivot point 46. Torsion bar 118 isapproximately 1.5 to 2.5 feet (45 to 76 cm) long and extends lengthwiseto attach to main frame 16. A similar arrangement provides the frontsuspension for the other front wheel.

Referring to FIG. 20, in another embodiment of the present invention, amain frame 122 is connected to a pivoting subframe 124 that incorporatesa front suspension system. Pivoting subframe 124 includes a left halfsubframe 124 a which is hingeably connected to a right half subframe 124b. Two hinges, such as a front clevis joint 135 and a rear clevis joint137, connect left and right half subframes 124 a, 124 b to each other. Afront pivot pin 146 acts as the clevis pin for front clevis joint 135while a rear pivot pin 148 acts as the clevis pin for rear clevis joint137. Front pivot pin 146 is connected to a front transverse member 147of main frame 122 via a front pivot plate 142, while rear pivot pin 148is connected to a rear transverse member 149 of main frame 122 via arear pivot plate 144.

A left spring pocket 140 a, connected to an extension of main frame 122,houses a left spring 138 a that abuts a front transverse portion 151 aof left half subframe 124 a, while a right spring pocket 140 b,connected to an extension of main frame 122, houses a right spring 138 bthat abuts a front transverse portion 151 b of right half subframe 124b. Thus, when a left caster wheel 136 a rolls into a dip, left halfsubframe 124 a moves with it, not affecting right half subframe 124 b ormain frame 122. Similarly, when a right caster wheel 136 b rolls into adip, right half subframe 124 b moves with it, not affecting left halfsubframe 124 a or main frame 122. Thus, three of the four mower wheelsare on the ground at any given time, resulting in a stable, smooth ridewith little or no scalping caused by the cutter deck.

In the embodiment illustrated in FIG. 20, rear suspension chains 153 fora cutter deck 150 are attached to rear wheel brackets 155 via a cutterdeck lift assembly 156, while front suspension chains 158 for cutterdeck 150 are attached via cutter deck lift assembly 156 to main frame122. The weight distribution in a lawn mower of this type isapproximately 75% in the rear and 25% in the front. Thus, whereas therear of the cutter deck is preferably connected to the rear wheelbrackets instead of the main frame to avoid scalping during sharp turnsor over rough terrain, the front of the cutter deck is preferablyconnected directly to the main frame in this embodiment.

FIGS. 21-26 illustrate another embodiment of the present invention. Thelawn mower 200 illustrated in FIGS. 21-26 includes a motor 202, a motorcover 204, a chassis 212, a front frame 214, a pair of front wheels 222,a pair of rear wheels 206 (only one of which is visible in FIG. 21), acutter deck 208, a seat 210, and a pair of front wheel independentsuspension assemblies 216. The particular type of lawn mower 200illustrated in FIG. 21 is presented by way of example only. In thisregard, the suspension systems of the present invention can be employedon any type of riding or non-riding lawn mower.

In the type of lawn mower illustrated in FIG. 21, the motor 202 ismounted to the chassis 212 and is covered by the motor cover 204. Also,the chassis 212 is mounted to the front frame 214, which can be aseparate frame connected to a rear frame (not shown) in any conventionalmanner or can define a front portion of a single frame of the lawn mower200. In some embodiments, the lawn mower 200 simply has a single frame214 upon which the motor 202 is mounted (whether by a chassis 212 orotherwise).

With reference to FIGS. 21 and 24, the rear wheels 206 of the lawn mower200 can be mounted to the chassis 212 by a pair of rear wheelindependent suspension assemblies 207, although the rear wheels 206 caninstead be rigidly mounted to the mower front frame 214, can beconnected to an axle that is pivotable with respect to the front frame214, or can be attached to the front frame 214 in any other manner.Examples of rear wheel independent suspensions 207 are provided in U.S.Pat. No. 6,244,025, the disclosure of which is incorporated herein byreference insofar as it relates to rear wheel independent suspensionsystems.

The cutter deck 208 of the lawn mower 200 can be in any location withrespect to the front and rear wheels 222, 206 and with respect to thefront frame 214. However, in the embodiment illustrated in FIG. 21, thecutter deck 208 is positioned between the front and rear wheels 222,206. The cutter deck 208 contains at least one cutter (not shown) forcutting grass or other vegetation on a surface, and in some embodimentscan be raised and lowered with respect to the ground.

The cutter deck 208 can be a floating or ground-following cutter deck.The cutter deck 208 according to the present invention can be directlyor indirectly connected to the frame of the lawn mower 200 in a numberof different manners, some of which provide different types of cutterdeck movement and cutter deck performance. For example, the cutter deck208 can be suspended entirely from the frame of the lawn mower 200, canbe suspended at the front and rear from front and rear independentsuspension systems, can be suspended from the front by front independentsuspension systems while being suspended from the rear by the frame ofthe lawn mower 200, or can be suspended from the rear by rearindependent suspension systems while being suspended from the front bythe frame of the lawn mower 200. Examples of the latter three types ofcutter deck suspensions are provided in the embodiments of the presentinvention illustrated in FIGS. 27-30, 31-34, and 21-26, respectively.

The floating cutter deck 208 illustrated in FIG. 21 is presented by wayof example only. In this embodiment, the cutter deck 208 is connected toand suspended from the front frame 214. Connection to the rearindependent suspension assemblies 207 permits the cutter deck 208 tofollow upward and downward movement of the rear wheels 206 in responseto changing terrain elevation, thereby maintaining the cutter deck 208in a more stable relationship with respect to the ground even as thelawn mower 200 traverses uneven terrain.

With continued reference to the embodiment of the present inventionillustrated in FIGS. 21-26, the front end of the cutter deck 208 is notresponsive to upward and downward movement of the front wheels 222.However, the rear end of the cutter deck 208 follows the upward anddownward movement of the rear wheels 206 by virtue of the cutter deck'sconnection to the rear independent suspension assemblies 207. Suchconnection can be established in a number of different manners, such asthe bolts 213 coupled at one end to respective brackets 219 on the rearend of the cutter deck 208 and to respective crank arms 221 pivotablycoupled to the rear independent suspension assemblies 207. In otherembodiments, the cutter deck 208 can be coupled to the rear independentsuspension assemblies 207 in any other manner desired, such as bysecuring chains, cables, links, straps, bars, or other elements to thecutter deck 208 and to the rear independent suspension assemblies 207.Further examples of manners in which the rear of the cutter deck 208 canbe directly or indirectly connected to the rear independent suspensionassemblies 207 are provided below with regard to front independentsuspension assemblies in FIGS. 27-30.

In the embodiment of the present invention illustrated in FIGS. 27-30,the mower 400 suspends the cutter deck 408 at one end from one or morefront independent suspension assemblies 416, and at another end from oneor more rear independent suspension assemblies 407. The cutter deck 408can be connected to the front suspension assemblies 416 for suspensiontherefrom in a number of different manners, such as by securing chains,cables, links, straps, bars, or other elements to the cutter deck 408and to the suspension assemblies 416. Such elements can be connected tothe suspension assemblies by bolts, screws, hooks, pins, or otherfasteners, by inter-engaging elements, and in some cases by permanentconnections such as welding, brazing, and the like. As will be describedin greater detail below, the elements employed to suspend the cutterdeck 408 from the suspension assemblies 416 can be connected directly tothe suspension assemblies or can be connected thereto via a deck liftingdevice (such as that shown in FIGS. 27 and 30). In this regard, theelements employed to suspend the cutter deck 408 from the suspensionassemblies 416 can be connected to one or movable or immobile levers,bars, or other elements connected to the suspension assemblies 416. Theelements employed to suspend the cutter deck 408 from the suspensionassemblies 416 can be connected to the cutter deck 408 in any mannerdesired, including the manners of connection described above withreference to connections to the suspension assemblies 416.

By way of example only, the cutter deck 408 illustrated in FIGS. 27 and30 is suspended by chains, each of which are connected at one end to aneyebolt on the cutter deck 408 and at another end to a crank arm 451pivotably connected to a corresponding suspension assembly 416 via amounting block 450. The mounting blocks 450 can be integral with orwelded to the second suspension arms 448, and in other embodiments canbe connected in other suitable manners, such as by clamping, bolting,and the like. In still other embodiments, the crank arm 451 can bepivotably connected to the suspension arm 448 by a post of the crank arm451 received within an aperture in the suspension arm 448 (or viceversa). It will be appreciated by one having ordinary skill in the artthat the chains employed to suspend the cutter deck 408 in suchembodiments can be coupled directly or indirectly to the suspension arm448 (or any other location on the independent suspension assembly 416)in a number of other manners, each of which fall within the spirit andscope of the present invention.

As mentioned above, the rear of the cutter deck 408 in the embodimentillustrated in FIGS. 27-30 is suspended from the rear independentsuspension assemblies 407. The rear of the cutter deck 408 can beconnected to the rear independent suspension assemblies in any of themanners described above with reference to the same connection in theembodiment illustrated in FIGS. 21-26, and the connections describedabove between the front of the cutter deck 408 and the front independentsuspension assemblies 416. By way of example only, and with particularreference to FIG. 30, the rear of the cutter deck 408 can be suspendedby chains 410 connected to bolts 453 on the cutter deck 408 and to rearcrank arms 452 pivotably connected to the rear independent suspensionassemblies 407.

By virtue of the suspended connections of the cutter deck 408 from thefront suspension assemblies 416, 417 (and if desired, from the rearindependent suspension assemblies 407), the cutter deck 408 can followupward and downward movement of the wheels 422, 406 in response tochanging terrain elevation, thereby maintaining the cutter deck 408 in amore stable relationship with respect to the ground even as the lawnmower 400 traverses uneven terrain.

In yet another embodiment of the present invention illustrated in FIGS.31-34, the cutter deck 508 is suspended at one end from frontindependent suspension assemblies 516, and at another end from the frame514. The front of the cutter deck 508 can be suspended from the frontindependent suspension assemblies 516 in any of the manners describedabove with regard to cutter deck suspension in the earlier embodiments.By way of example only, the front end of the cutter deck 508 is coupledto suspension arms 548 of the front independent suspension assemblies516 via front crank arms 551 pivotably coupled to the front independentsuspension assemblies (such as by front mounting blocks 550 welded tothe suspension arms 548 or otherwise connected thereto in any suitablemanner, such as by clamping, brazing, or integrally-forming the frontmounting blocks 550 with the suspension arms 548). As a result, thefront end of the cutter deck 508 is responsive and follows upward anddownward movement of the front wheels 522.

With continued reference to the embodiment of the present inventionillustrated in FIGS. 31-34, the rear end of the cutter deck 508 can besuspended from the frame 514 in any of the manners described above withregard to cutter deck suspension in earlier embodiments. By way ofexample only, the rear end of the cutter deck 508 is coupled to theframe 514 via rear crank arms 552 pivotably coupled to the frame 514(such as by rear mounting blocks 553). As a result, the rear end of thecutter deck 508 is not responsive to upward and downward movement of therear wheels 506.

In the embodiments illustrated in FIGS. 21-34, the cutter deck 208, 408,508 is attached to the front and/or rear independent suspension systemsin any manner desired, such as by chains or cables, by links, hinges orjoints, by conventional fasteners such as bolts, screws, rivets, hooks,clips, and the like. For example, in the embodiment illustrated in FIGS.21-26, the cutter deck 208 is coupled to the front frame 214 and rearindependent suspension assemblies 207 via deck hanger assemblies 209that include conventional threaded fasteners 223 passed through brackets225 on the cutter deck 208. As another example, in the embodimentillustrated in FIGS. 27-30, the deck hanger assemblies 409 includeconventional fasteners such as, for example, eyebolts, that are used inconjunction with chains to couple the cutter deck 408 to the front andthe rear suspension assemblies 416, 407. In the exemplary embodimentillustrated in FIGS. 30-34, the deck hanger assemblies 509 includeconventional fasteners such as, for example, U-bolts, that used inconjunction with chains to couple the cutter deck 508 with the frontsuspension assemblies 516 and the frame 514.

The deck hanger assemblies 209, 409, 509 can be attached directly to thefront and/or rear independent suspension assemblies (such as to arms,flanges, or other portions of the front and/or rear independentsuspension assemblies, within apertures in the front and/or rearindependent suspension assemblies, and the like), or can be indirectlyconnected thereto by cutter deck lifting assemblies 211, 411, 511. Forexample, the deck hanger assemblies 209, 409, 509 in the illustratedembodiments of FIGS. 21-34 are connected to bell cranks, arms, or otherelements movable by a user to lift and lower the cutter deck 208, 408,508 with respect to the ground. Such bell cranks, arms, and otherelements can be lifted and lowered by levers, pedals, cranks, motors,hydraulic or pneumatic actuators, or by any other manual or powereddevice. Still other devices and elements for raising and lowering acutter deck 208, 408, 508 are well known to those skilled in the art andare not therefore described further herein.

With reference again to the embodiment of the present inventionillustrated in FIGS. 22-26, the mower 200 can have a chassis 212, afront frame 214 (or front portion of a main frame 214), and a pair offront wheel independent suspension assemblies 216. The front frame 214can be connected to the chassis 212 by a plurality of bolts or otherthreaded fasteners 218. Other manners of fastening the front frame 214to the chassis 212 can instead be used. By way of example only, thefront frame 214 can be connected to the chassis 212 by screws, rivets,pins, welding or brazing, inter-engaging elements, and the like, and caneven be integral with the chassis 212 in some embodiments. For purposesof reference in the following description, a substantially horizontalaxis 220 runs through the center of the front frame 214 and chassis 212to divide the front frame 214 and chassis 212 into two sides. In someembodiments, the front frame 214 has opposite sides and has a front,each of which are defined by one or more beams, rods, bars, plates, orother structural members. For example, the front frame 214 in theillustrated embodiment is defined by tubular side beams 215 and atubular front beam 217 connected together by welds (although any othermanner of connecting these elements together can instead be employed,including those mentioned above with regard to connection of the chassis212 and frame 214). The side beams 215 in the exemplary embodiment ofFIGS. 21-26 are substantially parallel to the horizontal axis 220, whilethe front beam 217 is substantially orthogonal to the horizontal axis220. However, any other relative orientations of these beams 215, 217can instead be employed.

As will be appreciated by one having ordinary skill in the art, theframe 214 of the present invention can be constructed of a wide varietyof structural elements. In some embodiments, these elements includetubular beams as mentioned above. Tubular beams provide a relativelystrong and lightweight framework for the lawn mower 200 compared toother structural members that can be employed. In other embodimentshowever, the front frame 214 can be constructed partially or entirely ofdifferent structural members, including without limitation bars, rods,non-tubular beams having any cross-sectional shape (e.g., L-shapes,I-shapes, C-shapes, etc.), plates, and the like. Accordingly, as usedherein and in the appended claims, the term “beam” (whether referring tothe front beam 217, a side beam 215, or any other beam of the frontframe 214) is intended to encompass all of these structural members.

With continued reference to FIG. 22, the illustrated lawn mower 200 hasa pair of front wheel independent suspension assemblies 216 connected tothe front frame 214. Although the independent suspension assemblies 216can be different in structure, elements, and/or connection, bothindependent suspension assemblies 216 in the illustrated embodimentcontain identical components and are mirror images of each other withrespect to the horizontal axis 220. Each of the independent suspensionassemblies 216 has a ground-contacting wheel 222. However, theindependent suspension assemblies 216 can instead have other types ofrolling devices, including without limitation rollers, balls, and tiresconnected in any conventional manner for rotation and for support of thefront frame 214. For example, each of the caster wheels 222 can besupported by an axle 224 attached to an inverted yoke 226. Other typesof rolling element mounting methods are possible, such as a bent axleextending outward and upward from the axis of rotation of the rollingelement for connection to the rest of the independent suspensionassembly 216.

In some embodiments, each front wheel 222 is capable of pivoting about avertical or substantially vertical axis. In this regard, the frontwheels 222 can be pivotably connected to the rest of the frontindependent suspension assemblies 216 in a number of different manners.For example, the yokes 226 of the caster wheels 222 in the illustratedembodiment are pivotably connected to the rest of the front independentsuspension assemblies 216 by posts 228 extending vertically orsubstantially vertically from each yoke 226. These yokes 226 arepivotably connected to the rest of their respective suspensionassemblies 216 in any conventional manner. By way of example only, awasher 230, 237 and bearings 232, 235 are received on the posts 228 inthe illustrated embodiment, and enable the posts 228 and yokes 226 topivot with respect to the front frame 214.

Each front independent suspension assembly 216 illustrated in theembodiment of FIGS. 21-26 has a first suspension arm 246 connecting theassociated front wheel 222 to a front of the frame 214 and a secondsuspension arm 248 connecting the associated front wheel 222 to a sideof the front frame 214. The posts 228 in the illustrated embodiment arepivotably connected to the suspension arms 246, 248 by being receivedwithin and connected to a joint 236 connected to the suspension arms246, 248. Each joint 236 can take a number of different forms, and inthe embodiment of FIGS. 21-26 is a cylindrical member within which thepost 228 is received. Each post 228 is preferably secured within acorresponding joint 236 by a nut 238 or other threaded fastener screwedupon a threaded end of the post 228 as best shown in FIG. 22. Ifdesired, additional hardware can help secure this connection. Forexample, one or more cotter pins 240 can be clipped to the nut 238and/or post 228, can be received within an aperture or recess within thenut 238 and/or post 228, or can be connected to the post 228 in anyother conventional manner to prevent disconnection of the nut 238 fromthe post 228. As another example, one or more washers 237 can beprovided as needed to distribute force and secure the connection of theposts 228 to the joints 236.

As an alternative to the use of a cylindrical joint 236 as describedabove in order to connect the post 228 of each front independentsuspension assembly 216 to the suspension arms 246, 248, the joint 236can be a socket within which an end of the post 228 is received, can bedefined by an aperture in either or both suspension arms 246, 248, andthe like. Any conventional joint structure can be employed to establishthis connection of the post 228 and wheel 222, each of which fallswithin the spirit and scope of the present invention.

An advantage of a cylindrical joint 236 as described above is theability to receive bearings 232, 235 therein and to house and protectthe bearings 232, 235. In this regard, other elements and structure canbe used to enable the wheels 222 to pivot properly. For example,depending upon the type of joint 236 employed, ball bearings, rollerbearings, sleeves or linings made of low-friction material, and otherelements can be used as desired (with or without lubricating material).In the illustrated embodiment, two sets of roller bearings 232, 235 arereceived within the joint 236, and can be seated within lips, ledges, orother structure of the joint 236. However, any other manner of retainingthese and other types of bearings can be used, depending at leastpartially upon the type of joint 236 employed to connect the wheels 222with respect to the rest of the front independent suspension assemblies216.

Although a threaded connection is employed in some embodiments to securethe post 228 with respect to the rest of the front independentsuspension assembly 216, it should be noted that a number of other typeof connections can be used. By way of example only, the post 228 can besnap-fit, press-fit, or screwed into the joint 236 (or within a collar,lug, socket, or other fitting within the joint 36), can be assembled onopposite ends or sides of the joint 236 using any conventionalfasteners, and the like.

In some embodiments, it may be desirable to protect the joint 236 andits components from dirt, debris, and other foreign materials and toretain any lubricant material therein. To this end, the joint 236 can becapped, can be received within a boot, grommet, housing, or shroud, andthe like. For example the joint in the embodiment shown in FIGS. 21-26is covered with a cap 242.

As mentioned above, each front independent suspension assembly 216 inthe embodiment of FIGS. 21-26 has a first suspension arm 246 connectinga front wheel 222 to a front of the frame 214 and a second suspensionarm 248 connecting the front wheel 222 to a side of the front frame 214.The first suspension arms 246 can be connected at a common location onthe front of the frame 214 (whether by a common bolt 264 or otherfastener, by another common connection, or otherwise). Alternatively,the first suspension arms 246 can be connected to the front of the frame214 at different locations along the front of the frame 214.

In some embodiments, the first and second suspension arms 246, 248 areelongated tubular elements connected to form an acute angletherebetween. However, the first and second suspension arms 246, 248 caninstead be bars, beams, or other elongated elements that connected todefine an angle therebetween (and in some embodiments, an acute angletherebetween). The suspension arms 246, 248 can have any relativelength. In the illustrated embodiment for example, the first suspensionarm 246 is shorter than the second suspension arm 248. The suspensionarms 246, 248 in the embodiment of FIGS. 21-26 are welded to the joint236. In other embodiments, the suspension arms 246, 248 can be connectedto the joint 236 in any other manner, including without limitation bybrazing, by one or more conventional fasteners such as screws, bolts,rivets, clamps, clips, and the like, by pin and aperture, finger andslot, hook and aperture, and other types of connections, by threaded,press-fit, or snap-fit connections, by inter-engaging elements, and thelike.

As an alternative to direct connection to the joint 236, either or bothsuspension arms 246, 248 can be indirectly connected to the joint 236,such as by connection to a brace, strut, plate, reinforcement or otherelement connected to the joint 236, by connection of the firstsuspension arm 246 directly to the joint 236 and by connection of thesecond suspension arm 248 to the first suspension arm 246 (or viceversa), and the like.

The use of two suspension arms 246, 248 of each front independentsuspension enables connection of each front independent suspensionassembly 216 to two different locations on the front frame 214: (i) onelocation at the front of the frame 214 and one location at the side ofthe front frame 214, (ii) two locations at the front of the frame 214,or (iii) two locations at the side of the front frame 214. Although twosuspension arms 246, 248 are preferred for this purpose, one havingordinary skill in the art will appreciate that the same results can beachieved by using other elements and structures.

For example, the suspension arms 246, 248 can be replaced by a singlearm having a shape similar to the shape formed by two separatesuspension arms 246, 248. Also, the suspension arms 246, 248 can besupplemented by additional suspension arms to form a double wishbonesuspension system, including upper first and second suspension arms andlower first and second suspension arms. As an alternative to the mannerof connection illustrated in FIGS. 21-23, 25, and 26, such upper andlower first suspension arms may be connected to the front of the frame214 or the side of the front frame 214 along with the upper and lowersecond suspension arms. Additionally, the upper and lower first andsecond suspension arms can all be connected to the front of the frame214. As yet another example, a plate can be shaped to connect to thefront of the frame 214 and to extend around a front corner of the frame214 for connection to a side of the front frame 214. Still otherelements and structure can be employed to connect the joint 236 to thefront and side of the front frame 214, or to connect the joint 236 toonly the front or only the side of the front frame 214, each of whichfalls within the spirit and scope of the present invention.

Each of the suspension arms 246, 248 can be connected directly to thefront frame 214 in a number of different manners. In some embodiments,the suspension arms 246, 248 are pivotably connected to the front frame214 to enable upward and downward movement of the front independentsuspension assemblies 216. Any type of pivotable connection can beemployed, such a ball and socket connection, a pivot and apertureconnection, a hinge connection, and the like. One having ordinary skillin the art will appreciate that still other manners of pivotalconnection are possible. In the illustrated embodiment of FIGS. 21-26,both suspension arms 246, 248 are pivotably connected to the front frame214 by bolts 264 as will be described in greater detail below.

Although direct connection to the front frame 214 is possible, thesuspension arms 246, 248 in some embodiments are connected to plates,bars, rods, or other elements shaped to provide an improved interfacebetween the suspension arms 246, 248 and the front frame 214. Morespecifically, the suspension arms 246, 248 in many embodiments areoriented at an angle with respect to that part of the front frame 214 towhich they connect, thereby making such a connection more difficult.Therefore, the suspension arms 246, 248 of some embodiments areconnected to elements shaped to better establish an angled connection tothe front frame 214. In the illustrated embodiment of FIGS. 21-26 forexample, the first suspension arm 246 is connected to a suspension frontplate 250 on the front of the front frame 214, while the secondsuspension arm 248 is connected to a suspension side plate 251 of theside of the front frame 214. The suspension front and side plates 250,251 in this exemplary embodiment are welded to the front frame 214, butcan be connected thereto by fasteners or in any of the manners describedabove with reference to the connection between the first and secondsuspension arms 246, 248 and the joint 236. In some embodiments, thesuspension front and side plates 250, 251 can even be integral with thefront frame 214, such as by being stamped, molded, pressed, cast, orotherwise defined by a part of the front frame 214.

Each first suspension arm 246 can be pivotably connected to the front ofthe frame 214 (and in some cases, to a common suspension front plate 250as shown in FIGS. 21-26 or to respective suspension front plates) by afront pivot assembly 252. As mentioned above, the front pivot assembly252 can take a number of different forms. In the illustrated embodimentfor example, the front pivot assembly 252 includes a ball joint 260attached the first suspension arm 246 by a threaded fastener such as anut 258 threaded onto a threaded extension of the ball joint 260, a pairof joint seals 262, and a bolt 264 passed through apertures in the balljoint 260 and joint seals 262. If desired, a spacer 266 can be locatedbetween the ball joint 260 and the front plate 250 to provide clearancebetween the ball joint 260 and the front plate 250. The ball joint 260can instead be connected to the first suspension arm 246 by beingthreaded into a threaded aperture therein, by one or more conventionalfasteners, or in any of the manners described above with reference tothe connection between the first and second suspension arms 246, 248 andthe joint 236. Although not required, the joint seals 262 can beemployed for purposes of keeping the ball joint 260 free of dirt,debris, and foreign matter.

A bolt 264 can be employed for pivotable connection to the ball joint260 as described above. However, the bolt 264 can be replaced by anyother element received within the ball joint 260, including withoutlimitation a pin or rod, a headed post, extension, or any other elementextending into the ball joint 260 from the front plate 250 or frame 214.In other embodiments, a ball joint socket 260 be attached to the frontplate 250 or frame 214 and can pivotably receive a pin, rod, headedpost, extension, or other element attached to the first suspension arm246. The bolt 264 of the front pivot assembly 252 can extend into anaperture in the suspension front plate 250 and can be secured therein bya nut 268 or other conventional fastener.

As discussed above, the suspension front plate 250 can be shaped toconnect the first suspension arm 246 at an angle with respect to thefront of the frame 214. One having ordinary skill in the art willappreciate that a number of different front plate shapes can be employedto establish this angled connection. By way of example only, thesuspension front plate 250 can have a wing, flange, arm, tab, or otherportion 253 that provides a mounting location disposed at an angle withrespect to the front of the frame 214. In embodiments in which bothfront independent suspension systems are connected to a commonsuspension front plate 250 (see FIGS. 21-26), the suspension front plate250 can have two such portions 253 providing two mounting locationsdisposed at respective angles with respect to the front of the frame214. For different suspension and handling characteristics of the lawnmower 200, the first suspension arm 246 in some embodiments can beconnected to the suspension front plate 250 in one of two or moreprovided locations. By way of example only, the bolt 264 in theillustrated embodiment can be passed through one of a series ofapertures in the suspension front plate 250 (e.g., arranged in ahorizontal, vertical, or diagonal line, in a curved line, and the like).Connection to each different aperture can thereby provide a differentresting position of the front independent suspension assembly 216 toprovide different handling characteristics of the lawn mower 200.

With continued reference to FIGS. 22 and 23, the second suspension arm248 in the illustrated embodiment is mounted to the front frame 214 by aside pivot assembly 270. The side pivot assembly 270 in the illustratedembodiment has the same or similar elements as the front pivot assembly252. The second suspension arm 248 can be connected to the front frame214 via a suspension side plate 251. In some embodiments, the secondsuspension arm 248 is connected to a wing, flange, extension, tab, orother portion 272 of the suspension side plate 251 disposed at an anglewith respect to the side of the front frame 214 for the same reasonsdiscussed above. A bolt 264 can be received within a ball joint 260,joint seals 262, a spacer 276, and an aperture 274 in the suspensionside plate 251, and can be retained therein by a nut 268.

The alternative assemblies and elements described above with referenceto the connection between the first suspension arm 246 and thesuspension front plate 250 (or directly to the front frame 214 in otherembodiments) apply equally to the connection between the secondsuspension arm 248 and the suspension side plate 251 or front frame 214.

The front and side pivot assemblies 252 and 270 allow the suspensionarms 246, 248 to move in a substantially upward and downward verticaldirection relative to the front frame 214. Depending at least partiallyupon the lengths of the first and second suspension arms 246, 248 andthe location of their direct or indirect connection to the front frame214, other movement such as curved or horizontal movement is possible.

In some embodiments of the present invention, it is desirable tostrengthen the front independent suspension assemblies 216 and/or toprovide additional structure to which other elements, structure, anddevices of the front independent suspension assemblies 216 can beconnected. Such additional structure can include one or more plates,rods, bars, tabs, wings, extensions, bosses, platforms, struts, andother framework connected to the first suspension arm 246, the secondsuspension arm 248, and/or the joint 236. These elements and structurecan be connected to the suspension arms 246, 248 and joint 236 in anyconventional manner, including those manners described above withreference to the connection between the first and second suspension arms246, 248 and the joint 236. In the illustrated embodiment for example, asupport plate 278 is positioned between the first suspension arm 246 andthe second suspension arm 248 (either below the arms 246, 248 asillustrated in FIGS. 21-26, above the arms 246, 248, or on substantiallythe same level as the arms 246, 248) and can be welded to both arms 246,248.

Some embodiments of each front independent suspension assembly 216according to the present invention have a shock absorber 302 and/or asuspension spring 288. The shock absorber 302 and the suspension spring288 can be connected between the front frame 214 and the frontindependent suspension assembly 216 to absorb shock transmitted from thewheels 222 and to bias the front independent suspension assembly 216 ina downward direction.

The shock absorber 302 can be a conventional hydraulic shock absorber.However, the shock absorber 302 can take a number of other forms,including without limitation an air shock, an airbag, a coil, torsion,or other spring, and the like. Although the shock absorber 302 can beconnected in any conventional manner to the front frame 214 and to anypart of the front independent suspension assembly 216, the shockabsorber 302 in the embodiment illustrated in FIGS. 21-26 is locatedbetween and connected to the support plate 278 and the front frame 214(or a fixture on the front frame 214). In this regard, the shockabsorber 302 can be welded or brazed to the support plate 278 and frontframe 214, can be connected thereto with bolts, screws, rivets, pins,clips, clamps, or other conventional fasteners, or can be connectedthereto in any other manner desired. In some embodiments, the shockabsorber 302 can be received through an aperture 280 in the supportplate 278 for connection to a bottom or underside portion thereof.

In the embodiment illustrated in FIGS. 21-26, the shock absorber 302 hasa top mount 304 and a bottom mount 306, each mount 304 and 306 having anaperture 308 and 310, respectively, to receive fasteners 312 and 324therethrough. The fasteners 312, 324 (which can be bolts as shown in thefigures or can be any other conventional fastener desired) can bereceived through one or more apertures 286, 322 in the support plate 278and a bracket 320 extending from the front frame 214 and through theapertures 308, 310 in the top and bottom mounts 304, 306 of the shockabsorber 302. In some embodiments such as that shown in the figures, thesupport plate 278 can be shaped to define a bracket 282 for connectionto the bottom mount 306 of the shock absorber 302. Nuts 318, 332 orother fasteners can be employed to secure the fasteners 312, 324 onceinstalled. Additional hardware such as spacers 314, 316, 328, 330 andwashers 326 can be employed as needed to connect the shock absorber 302to the front frame 214 and to the rest of the front independentsuspension assembly 216.

The suspension spring 288 in the embodiment of FIGS. 21-26 is a coilspring that can be retained in position in a number of manners in orderto bias the rest of the front independent suspension assembly 216 in adownward direction. In some embodiments for example, the suspensionspring 288 is received upon a spring retainer 284 on the support plate278 and upon a spring retainer 290 connected to the front frame 214. Thespring retainers 284, 290 can be clips, clamps, or other elementsemployed to hold the spring 288 in place. In the embodiment illustratedin FIGS. 21-26, the spring retainers 284, 290 are inserts that arereceived within the ends of each spring 288 and are connected to thesupport plate 278 and the front frame 214 in any conventional manner. Inother embodiments, the spring retainers 284, 290 can be sockets withinwhich the ends of the springs 288 are received, recesses in the supportplate 278 and front frame 214 (or structure attached thereto), clamps,brazing, or welds holding either or both ends of the spring 288 inplace, and the like. Any other manner of holding the springs 288 inplace can instead be employed as desired.

As an alternative to connection of a spring retainers 284, 290 directlyto the support plate 278 and front frame 214, either or both of theseretainers 284, 290 can be connected to an adjusting element or devicefor changing the amount of compression of the spring 288. For example,the upper end of the springs 288 in the illustrated embodiments eachseat against an adjusting plate 292 received within a spring seat 294defined by the front frame 214 or connected to the front frame 214 inany conventional manner. The spring seat 294 can be provided with anaperture 296 within which is received an adjustment screw 298 or otherthreaded fastener. The screw 298 can be received through the spring seataperture 296 and into an aperture in the adjusting plate 292 so thatturning the screw 298 causes the adjusting plate 292 to compress orreduce the compression upon the spring 288. If desired, one or moreguides 299 can extend from the adjusting plate 292 to be received withinextensions of the spring seat aperture 296 or dedicated apertures inorder to prevent the adjusting plate 292 from turning with the screw298. Once the screw 298 has been turned to move the adjusting plate 292to a desired position, a nut 300 can be tightened on the screw 298 tohold the screw 298 and adjusting plate 292 in place.

Although the spring seat 294, adjusting plate 292, adjustment screw 298,and nut 300 are described above as being associated with an upper end ofthe spring 288, this type of adjustment mechanism can also or instead beprovided on the bottom end of the spring 288. In addition, it should benoted that a number of other spring adjustment mechanisms exist and canbe used to adjust compression of the springs 288 in the presentinvention. Each of these alternative spring adjustment mechanisms fallswithin the spirit and scope of the present invention.

As the front independent suspension assemblies 216 of the lawn mower 200travel in generally upward and downward vertical directions due to thefront and side pivot assemblies 252 and 270 traversing uneven terrain,the shock absorbers 302 (if used) dampen the shock delivered to themower front frame 214, chassis 212, and operator. This creates a morecomfortable ride for the operator, thereby allowing the operator to runthe mower 200 at more efficient speeds. The front independent suspensionassemblies 216 can also absorb a significant amount of vertical movementcaused by the uneven terrain, thereby preventing much of the verticalmovement of the front frame 214 and chassis 212. As a result, verticalmovement of the cutter deck 208 can be reduced to improve the cuttingperformance of the lawn mower 200. In addition, when one of the frontwheels 222 runs over a large rock, bump, dip, hole, or otherwiseexperiences a change in elevation causing the wheel 222 to movevertically upward or downward, the improved front independent suspensionassembly 216 of the present invention dampen the effect on the otherwheels. Thus, the wheels maintain better contact with the ground, givingthe lawn mower 200 better traction.

In many respects, the front suspension systems 416, 516 employed in theexemplary embodiments of the present invention illustrated in FIGS.27-30 and 31-34 are similar in construction and operation to thosedescribed above with reference to the embodiment illustrated in FIGS.21-26. Accordingly, with the exceptions described below and thosediscussed earlier, reference is hereby made to the description of theembodiment illustrated in FIGS. 21-26 for details regarding thesuspension systems 416, 516 illustrated in FIGS. 27-30 and 31-34.

In the embodiment of the present invention illustrated in FIGS. 27-30,the shock absorber 402 of each front suspension system 416 is locatedwithin the spring 488 of the same system 416. This shock absorber andspring assembly 454 is connected to the front suspension arm 446, andcan be secured thereto with flanges, bosses, plates, or other structureas desired. In addition, this shock absorber and spring assembly 454 isconnected to the frame 414 via a bracket 456 extending from the frame414, and is connected to the first suspension arm 446 via a bracket 455.Although the connection locations of the shock absorber and springassembly 454 can be located to position the shock absorber and springassembly 454 in a substantially vertical orientation, in someembodiments (such as that shown in FIGS. 27-30), the shock absorber andspring assembly 454 is instead oriented at acute angle toward the frame414.

In the embodiment illustrated in FIGS. 31-34, the shock absorber 502 ofeach front independent suspension system 516 is located within thespring 588 of the same system 516. The shock absorber and springassembly 554 is connected to the second suspension arm 548, and can besecured thereto with flanges, bosses, plates, or other structure asdesired. In addition, this shock absorber and spring assembly 554 isconnected to a pivotable mount 560, such as by using similar hardwareand methods of attachment as the shock absorber 302 of FIGS. 21-26 or inany other suitable manner.

The pivotable mount 560 can take a number of different forms, eachhaving a point about which the pivotable mount 560 pivots responsive toforce exerted by the shock and spring assemblies 554 in upward anddownward movement of the front independent suspension systems 516. Byway of example only, the pivotable mount 560 can be a beam, bar, rod,tube, plate, plate structure (see FIGS. 31-34), frame, or other elementcapable of pivoting about a pivot point and to which the frontindependent suspension systems 516 are connected. In some embodimentssuch as that shown in FIGS. 31-34, the pivotable mount 560 is pivotableabout an axis near or at a central longitudinal axis of the mower 500(although other pivot locations are possible). Also, in some embodimentsof the present invention such as that shown in FIGS. 31-34, the shockabsorber and spring assemblies 554 are connected at opposite ends of thepivotable mount 560 (although the shock absorber and spring assemblies554 need not necessarily be connected at ends of the pivotable mount 560to function as desired).

In some embodiments, the pivotable mount 560 is pivotably coupled to theframe 514 via conventional fasteners, and is responsive to upward anddownward movement of both front wheels 522. One or more spacers andother fastening elements can be employed to pivotably connect thepivotable mount 560 to the frame 514.

By connecting the front suspension systems 516 to the frame 514 via apivotable mount 560 as just described, the motion of each frontsuspension system 516 can be at least partially dependent upon themotion of the other front suspension system 516 (e.g., upward movementof one front wheel 522 generating downward force upon the other frontwheel 522). In some embodiments, the shock absorber and springassemblies 554 are replaced by one or more bars, tubes, beams, or otherstructure absorbing little or no motion of either front wheel 522,thereby transmitting motion of one front wheel 522 to the other frontwheel 522. However, a higher degree of independent movement of the frontwheels 522 is enabled by connecting the front wheel suspension systems516 to the pivotable mount 560 via shock absorbers 502 and/or springs588, both of which can dampen the transmission of one wheel's motion tothe pivotable mount 560 and to the other front wheel 522.

In some embodiments, the connection of the front independent suspensionsystems 516 to a pivotable mount 560 as described above providesimproved traction for the rear wheels 506 of the mower 500.

One having ordinary skill in the art will also recognize that a numberof the elements and structure in the embodiments described can bereplaced by other elements and structure performing the same functionsand still falling within the spirit and scope of the present invention.For example, while a number of lawn mower embodiments used in connectionwith the present invention have the cutter deck positioned between thefront and rear wheels, the present invention is also applicable tomowers having a cutter deck cantilevered from the chassis so that it islocated forward or rearward of the front or rear wheels, respectively.Also, the springs 288, 488, 588 described above and illustrated in thefigures are helical compression springs. One having ordinary skill inthe art will appreciate that other types of springs can instead beemployed with the front independent suspension assemblies 216, 416, 516of the present invention, such as torsion bars and other torsionsprings, leaf springs, and the like. Each of these alternative springscan be positioned between the frame 214, 414, 514 and the frontindependent suspension assemblies 216, 416, 516 in order to provide thedesired downward force upon the front wheels 222, 422, 522.

Furthermore, the various embodiments of the present invention shown inFIGS. 21-34 can include alternate elements and alternate structure thatare different in appearance and/or form than those illustrated, but thatstill perform the same or similar functions. Such alternate elements andstructure fall within the spirit and scope of the present invention.

The present invention is also applicable to lawn mowers having more orfewer than four wheels and to lawn mowers designed for the operator towalk or ride behind or in front of the mower. By way of example only,the present invention finds applicability to walk-behind mowers, pushmowers, and mowers with seats cantilevered forward or rearward of thefront or rear wheels, respectively.

Accordingly, the embodiments described above and illustrated in thefigures are presented by way of example only and not intended as alimitation upon the concepts and principles of the present invention. Assuch, it will be appreciated by one having ordinary skill in the artthat various changes in the elements and their configuration andarrangement are possible without departing from the spirit and scope ofthe present invention as set forth in the appended claims.

1. A mower, comprising: a chassis having a front portion and a rearportion; a prime mover mounted on the chassis; a cutter deck supportedby the chassis; front wheels attached to the front portion of thechassis; two drive wheel assemblies on different sides of the rearportion of the chassis, each drive wheel assembly connected to thechassis by at least one link pivotable with respect to the chassis; atleast one biasing member associated with the drive wheel assemblies andpositioned to bias the drive wheel assemblies in a downward direction,the biasing member being constructed of a non-metal material; whereinthe drive wheels and front wheels support the chassis for movement overa surface; each drive wheel assembly comprising a drive wheel poweredfor rotation by the prime mover; and wherein each drive wheel assemblymoves up and down relative to the chassis, respectively against and withforce exerted by the at least one biasing member, independently ofmovement of the other drive wheel assembly.
 2. The mower as claimed inclaim 1, wherein the cutter deck is suspended from the chassis betweenthe front portion and rear portion of the chassis, and wherein thecutter deck hangs at a predetermined distance from the chassis, thecutter deck being movable upwardly under influence of an upward force.3. The mower as claimed in claim 1, wherein each drive wheel assemblycomprises a motor independently powered by the prime mover.
 4. A mower,comprising: a chassis having a front portion and a rear portion; a primemover mounted on the chassis; a cutter deck supported by the chassis;front wheels attached to the front portion of the chassis; two drivewheel assemblies on different sides of the rear portion of the chassis,each drive wheel assembly connected to the chassis by at least one linkassembly; each link assembly pivotably connected at an inner end to apivot point on the chassis and pivotably connected at an outer end to apivot point on the wheel assembly; at least one biasing member coupledto each drive wheel assembly, the biasing member being constructed of anon-metal material; wherein the drive wheels and front wheels supportthe chassis for movement over a surface; each drive wheel assemblycomprising a drive wheel rotated by the prime mover; and wherein eachdrive wheel assembly moves relative to the chassis, respectively againstand with force exerted by the biasing member, independently of movementof the opposing drive wheel assembly.
 5. A mower comprising; a chassishaving a front portion, a rear portion, and a longitudinal axis; asubframe pivotably connected to the front portion of the chassis forpivoting about the longitudinal axis and adapted to receive two frontwheels; a prime mover mounted on the chassis; the two front wheelsattached to different sides of the subframe; two drive wheel assemblies,one each on different sides of the rear end of the chassis and connectedthereto by at least one link assembly, each link assembly comprising atleast one link pivotably connected at an inner end to a pivot point onthe chassis and pivotably connected at an outer end to a pivot point onthe wheel assembly, each drive wheel assembly comprising a wheel drivenby the prime mover; a biasing member pressing on each wheel assembly forurging the wheel assembly downwardly, the biasing member beingconstructed of a non-metal material; and wherein each drive wheelassembly moves up and down relative to the chassis, respectively againstand with force exerted by the biasing member, independently of movementof the opposing wheel assembly.
 6. The mower as claimed in claim 5,further comprising a cutter deck suspended beneath the chassis betweenthe front and rear wheels by a deck hanger, the deck hanger holding thecutter deck beneath the chassis and limiting the downward movement ofthe deck to a predetermined distance while enabling the deck to moveupwardly under the influence of an upward force.
 7. The mower as claimedin claim 5, wherein each drive wheel assembly comprises a motorindependently powered by the prime mover.
 8. The mower as claimed inclaim 5, wherein each drive wheel assembly further comprises a motorpowered by the prime mover, and wherein variation of relative speed ofthe drive wheels of the two wheel assemblies alters the direction oftravel of the mower.
 9. A mower, comprising: a chassis; a prime movermounted on the chassis; a cutter deck supported from the chassis; twopairs of wheels, one each attached to the chassis at different endsthereof; wherein: the wheels support the chassis for movement over asurface, one of the pairs of wheels comprises drive wheels rotated bythe prime mover; and each of the one pair of drive wheels is attached tothe chassis by at least one link assembly pivotably connected to thechassis and the drive wheel; and each drive wheel moves up and downrelative to the chassis, respectively against and with force transmittedto the wheel by a biasing member, independently of movement of the otherwheel of the pair, the biasing member being constructed of a non-metalmaterial.
 10. The mower as claimed in claim 9, wherein each drive wheelis independently rotated by the prime mover, and wherein change inrelative rotational speed of the drive wheels alters the direction oftravel of the mower.
 11. The mower as claimed in claim 9, wherein the atleast one link assembly causes each drive wheel to move vertically upand down without change in camber.
 12. The mower of as claimed in claim9, wherein the cutter deck is suspended from the chassis, whereby thecutter deck is movable in an upward direction relative to the chassiswhen an upward force is applied to the deck portion; the mower furthercomprising a lifting bracket coupled to the cutter deck for lifting thedeck portion upwardly when a drive wheel moves upwardly.